Bottom level detection device for burst mode optical receiver

摘要

A bottom level detection device is disclosed for a burst mode optical receiver. The receiver includes a converter for converting a burst mode signal into a voltage signal and an automatic gain controller for automatically controlling a gain of the converter. The bottom level detection device detects a bottom level of an output signal from the converter and controls the automatic gain controller on the basis of the detected bottom level. The bottom level detection device includes an amplification circuit (50) for receiving the output signal from the converter at its first input terminal (IN) and a fed-back output signal from the device (OUT) at its second input terminal, respectively, and amplifying a difference between the received signals, a detector (60) for detecting a bottom level of an output signal from the amplification circuit, and an output buffer (70). The detector includes an RC rectifier (Rc,Cc) for receiving a power supply voltage (Vcc), and a transistor having its emitter connected to an output terminal of the amplification circuit and its base and collector connected in common to the RC rectifier. <IMAGE>